Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Bougamont, Marion; Bamber, Jonathan; Ridley, Jeff; Gladstone, Rupert; Greuell, Wouter; Hanna, Edward; Payne, Anthony; Rutt, I. C.

doi:10.1029/2007gl030700

Cited by 89 publications

(88 citation statements)

References 29 publications

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“…However, it is clear from the literature that unlike a dry , the uncertainty in the ice albedo as seen from an SMB model is greater than the observational uncertainty. Previous publications report values of 0.4, 0.58, 0.4, 0.34 and 0.5 for a ice used in full EB SMB models [Bougamont et al, 2007;Greuell and Konzelmann, 1994;Mernild et al, 2008;Oerlemans and Knap, 1998;Pritchard et al, 2008]. Paterson [1994b] also quotes a possible ice albedo range of 0.3-0.5.…”

Section: A12 Parameter a Icementioning

confidence: 99%

Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet

et al. 2012

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[1] Computational modeling of Earth system processes often requires simplifying assumptions of the real system. These necessary assumptions result in the definition of internal model parameters that can take a number of different values but must be explicitly defined for any one model simulation. The main issue with such an uncertain multidimensional input space is that many simulations are needed to adequately explore it. This study presents a generalized parameter screening experiment for use in future earth system modeling. This approach identifies model parameters that dominate uncertainty, therefore reducing to a manageable number the simulations required to explore the input space. The approach we adopt is relatively inexpensive to implement and can be applied at both the aggregate and disaggregate (e.g., regional) level. To demonstrate the potential of such a method, it is applied to a surface mass balance model of intermediate complexity over the Greenland ice sheet. All identified parameters were related to the surface melt parameterization, with albedo parameters being identified as the most important. Spatial distributions of the parameter sensitivities show that, in recent years, most parameter sensitivities are concentrated around the southwest and northern ice sheet margins. Simulations for the 21st century indicate an increase in sensitivity in these high melt areas especially in the northeast. Melt contributions from temperature and radiative effects are shown to be important on the order of parameters identified, and as a consequence, sensitivities are dependent on the present climate used for modeling surface mass balance.Citation: Fitzgerald, P. W., J. L. Bamber, J. K. Ridley, and J. C. Rougier (2012), Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet,

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Section: A12 Parameter a Icementioning

confidence: 99%

Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet

et al. 2012

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“…Such a threshold is generally confirmed in coupled ice-sheet simulations. The temperature range may be larger when additional uncertainty from the melt model is included (Bougamont et al 2007); however, Stone et al (2010) find the threshold to be substantially lower using new boundary conditions for ice-sheet geometry, surface temperature and precipitation. For sustained 49 CO 2 forcing, corresponding to a mean Greenland warming of around 8°C, Ridley et al (2005) find deglaciation to take around 3,000 years to complete using Had-CM3.…”

Section: Introductionmentioning

confidence: 99%

Response of the Greenland and Antarctic Ice Sheets to Multi-Millennial Greenhouse Warming in the Earth System Model of Intermediate Complexity LOVECLIM

et al. 2011

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Calculations were performed with the Earth system model of intermediate complexity LOVECLIM to study the response of the Greenland and Antarctic ice sheets to sustained multi-millennial greenhouse warming. Use was made of fully dynamic 3D thermomechanical ice-sheet models bidirectionally coupled to an atmosphere and an ocean model. Two 3,000-year experiments were evaluated following forcing scenarios with atmospheric CO 2 concentration increased to two and four times the pre-industrial value, and held constant thereafter. In the high concentration scenario the model shows a sustained mean annual warming of up to 10°C in both polar regions. This leads to an almost complete disintegration of the Greenland ice sheet after 3,000 years, almost entirely caused by increased surface melting. Significant volume loss of the Antarctic ice sheet takes many centuries to initiate due to the thermal inertia of the Southern Ocean but is equivalent to more than 4 m of global sea-level rise by the end of simulation period. By that time, surface conditions along the East Antarctic ice sheet margin take on characteristics of the present-day Greenland ice sheet. West Antarctic ice shelves have thinned considerably from subshelf melting and grounding lines have retreated over distances of several 100 km, especially for the Ross ice shelf. In the low concentration scenario, corresponding to a local warming of 3-4°C, polar ice-sheet melting proceeds at a much lower rate. For the first 1,200 years, the Antarctic ice sheet is even slightly larger than today on account of increased accumulation rates but contributes positively to sea-level rise after that. The Greenland ice sheet loses mass at a rate equivalent to 35 cm of global sea level rise during the first 1,000 years increasing to 150 cm during the last 1,000 years. For both scenarios,

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“…However, the use of a PDD-model to derive ablation generally leads to overestimation of the climate sensitivity ( Van de Wal, 1996), due to spatial and temporal variability of the degree-day factors (Van den Broeke et al, 2010) and not explicitly accounting for changes in e.g. lapse rates and albedo feedbacks in a transient climate (Bougamont et al, 2007). In view of the complexities that determine the spatial and temporal evolution of SMB, its inclusion in ice sheet models needs improvement.…”

Section: Introductionmentioning

confidence: 99%

Coupling of climate models and ice sheet models by surface mass balance gradients: application to the Greenland Ice Sheet

et al. 2012

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Abstract. It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation from a climate model, and parameterizing the meltwater run-off as a function of temperature, which is often related to surface elevation (H s ). In this study, we propose a new strategy to calculate SMB, to allow a direct adjustment of SMB to a change in ice sheet topography and/or a change in climate forcing. This method is based on elevational gradients in the SMB field as computed by a regional climate model. Separate linear relations are derived for ablation and accumulation, using pairs of H s and SMB within a minimum search radius. The continuously adjusting SMB forcing is consistent with climate model forcing fields, also for initially non-glaciated areas in the peripheral areas of an ice sheet. When applied to an asynchronous coupled ice sheet -climate model setup, this method circumvents traditional temperature lapse rate assumptions. Here we apply it to the Greenland Ice Sheet (GrIS). Experiments using both steady-state forcing and glacial-interglacial forcing result in realistic ice sheet reconstructions.

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Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Cited by 89 publications

References 29 publications

Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet

Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet

Response of the Greenland and Antarctic Ice Sheets to Multi-Millennial Greenhouse Warming in the Earth System Model of Intermediate Complexity LOVECLIM

Coupling of climate models and ice sheet models by surface mass balance gradients: application to the Greenland Ice Sheet

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